Mazhanadu
Mazhanadu is a region between Tondai Nadu and Karnataka which was called as Mazhavarnadu. This region falls under the great ancient dynasty called Chera Dynasty. It includes the Districts of Salem, Namakkal, Dharmapuri and Krishnagiri. In ancient sangam age this region was ruled by Mazhavar King Kolli Mazhavan. Famous Sangam poetess Avvaiyar had cordial relation with the Mazhavar chieftains like Athiyamān Nedumān Añci of Thagadoor and Valvil Ori of Kollimalai. Mazhanadu was divided into two major divisions namely Mel-Mazhanadu and Keezh-Mazhanadu. The Keezh-Mazhanadu was once ruled by Kolli Mazhavan and his successors. The Keezh-Mazhanadu was well known by its water resources. It was mentioned in a Tamil poem.Mazhanadu region
The table below lists geographic and demographic parameters for districts that constitute the 'Mazhanaduregion' of Tamil Nadu.
| S.No. | Districts | Headquarters | Established | Area | Population | Population density |
| 1 | Salem | Salem | 1 November 1956 | 5,205 | 3,482,056 | 669 |
| 2 | Dharmapuri | Dharmapuri | 2 October 1965 | 4,497.77 | 1,506,843 | 335 |
| 3 | Namakkal | Namakkal | 1 January 1997 | 3363 | 1,726,601 | 513 |
| 4 | Krishnagiri | Krishnagiri | 9 February 2004 | 5,143 | 1,879,809 | 366 |
